Because of advances in micro-circuitry and multimedia technology, digital cameras are now in widespread used. High-end portable electronic devices, such as mobile phones and Personal Digital Assistants (PDAs), are being developed to be increasingly multi-functional. Many of these portable electronic devices are popularly equipped with digital cameras. To facilitate portability, such portable electronic devices tend to be compact, slim, and light. Accordingly, digital cameras incorporated in the portable electronic devices have also been reduced in size and weight, yet remain cost-effective.
Referring to FIG. 3, a typical related digital camera module 1 includes a lens module 2, a lens holder 3, and an image sensor chip 4. The lens holder 3 is a hollow chamber. The lens module 2 includes a barrel 21 and a lens 22 received in the barrel 21. The barrel 21 is partially received in and is threadingly engaged with the lens holder 3. An infra-red (IR) cut filter 6 is adhered to a top surface of the image sensor chip 4 to protect the image sensor chip 4 against damage from IR light. The image sensor chip 4 is typically attached onto a printed circuit board 5. The image sensor chip 4 has a photosensitive area 41 formed on the top surface 40 thereof. The photosensitive area 41 is configured for receiving light signals transmitted through the lens module 2. A plurality of chip pads is formed on the top surface 40 for surrounding the photosensitive area 41. A plurality of bonding pads is formed on the printed circuit board 5 to electrically connect to the corresponding chip pads via wires. A plurality of elements 7 is adhered on the periphery of the printed circuit board 5 around the bonding pads. The lens holder 3 is mounted on the printed circuit board 5 so that the image sensor chip 4, the chip pads, the bonding pads, and the wires are received therein.
However, during operation of the camera module 1, a digital chip or radio frequency (RF) circuit of the element 7 adhered on the printed circuit board 5 generates electromagnetic waves. Thus, the electromagnetic waves can affect electric signals converted by the image sensor chip 4, thereby the image transmitted to a display unit, such as an LCD, is impacted. In addition, in the camera module 1, the printed circuit board 5 needs to provide sufficient space not only for the image sensor chip 4, the element 7, and the wires but also to for the mounting of the lens holder 3. To minimize the size and volume of the camera module 1 to a certain degree, an end portion 32 of the lens holder 3 is made thin. However, such a thin lens holder 3 is not easily manufactured by an injection molding method. This difficulty results in a relatively high cost. As such, the camera module 1 has not proven to be economically suitable for slim and compact electronic products.
What is needed, therefore, is a camera module that is not only compact and prevent external electromagnetic waves from being introduced into the camera module, but also economical to produce.